JP2009100324A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device, controlling whether or not correction on signal differences caused in image data due to a boundary area of an image pickup element is performed based on a predetermined condition in the case of performing through image display. <P>SOLUTION: This imaging device includes: the image pickup element 10 for imaging an object light and outputting an image pickup signal; a display unit 17, which displays a through image based on the image data generated from the image pickup signals; a specifying unit 19, which specifies an enlarged display area of the through image in the display unit; a determination unit 11, which determines whether or not the enlarged display area specified by the specifying unit is a predetermined designated area; and a correction unit 15, which performs a correction processing on signal differences generated in the image data when the designated area is decided by the determination unit and execution of enlarged display is designated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus that displays a through image based on image data generated from an imaging signal.

In recent years, in a digital single-lens reflex camera, a large-sized (large imaging area) imaging device such as a 35 mm full-size imaging device is mounted. The manufacturing process of the image sensor includes a photolithography process. However, in an exposure apparatus (stepper or the like) used in the photolithography process, an exposure area that can be exposed at one time is limited. When manufacturing the substrate, the exposure area of the substrate to be exposed is shifted as necessary, and divided exposure is performed in multiple steps (when manufacturing at least one of the semiconductor layer, color filter layer, and microlens layer) Split exposure) (see Patent Document 1). Therefore, there is a case where a signal level difference (signal unevenness) based on the boundary region due to the divided exposure process at the time of manufacture occurs in the image data based on the image pickup signal output from the large image pickup device manufactured as described above. In the image peripheral region, signal unevenness may occur due to the manufacturing process. Furthermore, some image sensors have pixel defects, and signal unevenness may occur even in the pixel defect region.
JP 2006-73624 A

  By the way, in the case of taking a still image, a signal step generated in the image data due to the boundary region of the image sensor is corrected by the signal processing unit so as to be inconspicuous on the image. Even in the case where the above correction is performed, if the above correction is always performed, the load on the signal processing unit is increased and problems such as heat generation may occur.

  An object of the present invention is to provide an imaging device that controls whether or not to correct signal unevenness generated in image data in a boundary region of an imaging element or the like based on a predetermined condition when displaying a through image. It is to be.

  In the following, the configuration of the present invention will be described with reference to one embodiment, but the present invention is not limited to the configuration of the present embodiment.

  The imaging device of the present invention includes an imaging element (10) that images subject light and outputs an imaging signal, a display unit (17) that displays a through image based on image data generated from the imaging signal, A designation unit (19) for designating an enlarged display area of the through image in the display unit, and a discrimination unit for discriminating whether or not the enlarged display area designated by the designation unit is a predetermined area (predetermined) 11) and a correction unit (15) that performs a process of correcting signal unevenness that occurs in the image data when the determination unit determines that the predetermined region is specified and execution of enlargement display is instructed. And

  According to the imaging apparatus of the present invention, when displaying a through image, whether or not to correct signal unevenness such as a signal level difference generated in image data due to a boundary region of the imaging element is enlarged. Since control is performed according to the magnification of the display area and the through image, signal unevenness generated in the image data can be corrected only when necessary, and the load on the signal processing unit or the like is increased based on the correction of signal unevenness. The through image can be displayed for a long time with a good image quality.

  Hereinafter, an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a digital camera 2 according to the embodiment. As shown in FIG. 1, the digital camera (imaging device) 2 is provided with an imaging device 10 composed of a CCD or a CMOS, and the imaging device 10 is driven by an imaging device drive circuit 12 controlled by a CPU 11. Then, an imaging signal (analog signal as accumulated charge) obtained by imaging subject light via a photographing lens (not shown) is output. The image sensor 10 is a 35 mm full size (24 mm × 36 mm) image sensor, and has a boundary region caused by a divided exposure process at the time of manufacture (see FIG. 2).

  The imaging signal output from the imaging element 10 is input to the A / D conversion circuit 14 via the analog signal processing circuit 13, converted into a digital signal by the A / D conversion circuit 14, and input to the previous signal processing unit 15. Is done. The pre-signal processing unit 15 performs image processing such as white balance adjustment, contour compensation, and gamma correction on the image data based on the imaging signal output from the A / D conversion circuit 14, and an LCD described later based on the image data. When a through image is displayed on the display unit 17, a signal level difference (signal unevenness) generated in image data due to a boundary region or the like generated due to a divided exposure process at the time of manufacturing the image sensor 10 is corrected. That is, when the image sensor 10 is manufactured, an area in the image sensor surface is divided, and exposure is performed in different processes for each area. Therefore, there may be a difference in output intensity of the image signal for each area. Therefore, the signal level difference (signal unevenness) based on the difference in output intensity is corrected. Further, since signal unevenness also occurs in the peripheral region (image peripheral region) and the image defect region of the image sensor 10 shown in FIG. 2, the signal unevenness in these regions is corrected. The image data that has undergone signal processing in the previous signal processing unit 15 is input to the signal processing unit 16 via the CPU 11 and subjected to thinning correction or the like when displaying a through image. An image is displayed.

  Further, the CPU 11 includes a temperature sensor 18 for detecting the temperature of the image sensor 10 or the vicinity thereof, an operation unit 19 provided with a power button, a selection button, a release button, and the like, and a region for correcting signal unevenness (signal unevenness correction). A storage unit 20 is stored which stores the boundary region, the image peripheral region and the pixel defect region, which are caused by the divisional exposure process at the time of manufacturing, and the correction amount of the signal unevenness for each correction region. Has been. In addition, it is designed in advance which part of the image sensor 10 has a boundary region and a signal level difference (signal unevenness) occurs, and in which region (image peripheral region) of the image sensor 10 the signal unevenness occurs. It is known in terms of value, and by performing trial imaging before shipment, it is possible to know the amount of signal unevenness at each position in the boundary region of the image sensor 10 and at each position in the periphery of the image sensor. Therefore, before shipment, the positions of the boundary region and the image peripheral region of the image sensor 10 are stored in the storage unit 20 as the signal unevenness correction region, and the signal unevenness correction amount for each signal unevenness correction region is stored. Further, since the position of the pixel defect area of the image sensor 10 and the amount of signal unevenness in the pixel defect area can be known by trial imaging, the position of the pixel defect area of the image sensor 10 and The amount of signal unevenness correction in the pixel defect area is stored.

  Next, the operation of the digital camera 2 according to the embodiment will be described with reference to the flowchart of FIG. First, a power button (not shown) provided on the operation unit 19 is operated to turn on the digital camera 2, and a through image is displayed using a selection button (not shown) provided on the operation unit 19. When the display mode is selected, display of a through image is started on the LCD display unit 17 (step S10). Here, when the power of the digital camera 2 is turned on and the through image display mode is selected, the enlargement magnification of the through image display is set to 1 so that the image is output from the image sensor 10. A through image is displayed on the LCD display unit 17 using image data obtained by thinning out image data based on the imaging signal at a predetermined rate (for example, image data having a thinning rate of 2/3).

  FIG. 4 shows a state in which color filters (R (red), G (green), B (blue)) are arranged for each pixel of the image sensor 10 by a Bayer array, and are output from the image sensor 10. When the thinning rate of the image data based on the imaging signal is 2/3, the pixel corresponding to the image data used for displaying the through image is circled. The thinning rate is indicated by the number of pixels to be thinned out with respect to the total number of pixels of the image sensor 10, and when the thinning rate is 2/3, 2/3 of the pixels from the whole pixels are in the row direction and the column direction. The pixels are thinned out at equal intervals and 1/3 of the total number of pixels is used for displaying a through image.

  Here, when the enlargement magnification of the through image is set to 1, for example, since the thinning rate is set to 2/3 in advance, the signal processing unit 16 determines from the image data H2 shown in FIG. Image data corresponding to the pixels in the H3, H5, H6, H8, H9, H11, H12, H14, and H15th rows is thinned out, and further, V2, V3, V5, V6, V8, V9, V11, V12, V14, Image data corresponding to the pixels in the V15th column is thinned out, and image data having a thinning rate of 2/3 is generated. In this case, since the image data does not include image data corresponding to pixels in the V8 and V9 columns adjacent to the boundary region of the image sensor 10, stitching correction (signal unevenness correction) described later is performed. Absent. Thus, when thinning out image data, stitching correction (signal unevenness correction) can be omitted by thinning out pixels (pixel columns) adjacent to the boundary region. It should be noted that since which part of the image sensor 10 has the boundary region (which pixel is adjacent to the boundary part) is stored in the storage unit 20 in advance, the boundary part adjacent to the storage part 20 is stored. A pixel for thinning out image data is determined using information on the position of the pixel. In addition, when the image data is thinned, by referring to the position of the pixel defect area stored in the storage unit 20 and thinning out the pixels in the pixel defect area, correction of signal unevenness occurring in the pixel defect area can be omitted. Can do.

  While the through image is displayed on the LCD display unit 17, an enlargement display area of the through image is designated by a selection button (not shown) provided on the operation unit 19 (step S11), and an enlargement magnification is designated (step S11). S12) When execution of enlargement display of the through image is instructed (step S13), it is determined whether or not the designated enlargement display area is a predetermined area (signal unevenness correction area) stored in the storage unit 20. Is performed (step S14). That is, it is determined whether or not the designated enlarged display area is a predetermined area that is stored in the storage unit 20 and includes any of the boundary area, the image peripheral area, and the pixel defect area of the image sensor 10. As shown in FIG. 5, for example, when the area A is designated as the enlarged display area, the area A includes a predetermined area stored in the storage unit 20, and thus the process proceeds to step S15. In step S15, the signal unevenness correction amount stored in the storage unit 20 is referred to as a reference for determining whether or not to correct the signal unevenness in the designated predetermined area.

  If the area B shown in FIG. 5 is designated as the enlarged display area, the area B does not include the predetermined area stored in the storage unit 20, and thus the process proceeds from step S14 to step S18. In the LCD display unit 17, the through image is enlarged and displayed at the enlargement magnification designated in step S12.

  On the other hand, in step S16, it is determined whether or not to perform signal unevenness correction based on the magnification specified in step S12 and the signal unevenness correction amount referenced in step S15. That is, for example, if the signal unevenness correction amount is small and the enlargement magnification is small, the influence of the signal unevenness on the image quality of the through image is small and the process proceeds to step S18 without correcting the signal unevenness. On the other hand, when the signal unevenness correction amount is small and the enlargement magnification is large, since the signal unevenness has a large influence on the image quality of the through image, the process proceeds to step S17 to correct the signal unevenness.

  If it is determined in step S16 that the signal unevenness is to be corrected, the signal unevenness is corrected so that the signal unevenness does not affect the image quality of the through image (step S17). In this case, since the region A includes a boundary region generated due to the divided exposure process at the time of manufacturing the image sensor 10, signal unevenness correction (stitching correction) generated in the boundary region is performed.

  When performing the stitching correction, as shown in FIG. 6, first, sampling points are set at predetermined intervals along the boundary region of the image sensor 10, and r (r is a predetermined natural number) pixels in each of the vertical and horizontal directions for each sampling point. The local region 140 is set. The local region 140 is divided into a left region 141 and a right region 142 at the boundary region of the image sensor 10, and in the left region 141, the respective left average values of the output components of R, Gr, Gb, and B are obtained and the right region In 142, the right average values of the output components of R, Gr, Gb, and B are obtained. Here, the Gr pixel is an output component of the G pixel existing in the R pixel row (the row where the R pixel is present), and the Gb pixel is the G pixel existing in the B pixel row (the row where the B pixel is present). Is the output component.

  Next, the right / left ratio of the signal level difference is calculated for each sampling point to obtain a stitch correction coefficient. That is, the stitch correction coefficients for the R, Gr, Gb, and B components are calculated as follows.

R component stitch correction coefficient = (R component left average value) / (R component right average value)
Gr component stitch correction coefficient = (left average value of Gr component) / (right average value of Gr component)
Gb component stitch correction coefficient = (left average value of Gb component) / (right average value of Gb component)
B component stitch correction coefficient = (B component left average value) / (B component right average value)
Here, since it is assumed that the right side of the boundary region is corrected, the stitch correction coefficient is obtained using the left average value as the numerator and the right average value as the denominator.

  A slope change for converging the stitch correction coefficient calculated for each sampling point to 1 with a predetermined width in a direction orthogonal to the boundary region is generated for each sampling point, and the slope change is complemented in the extending direction of the boundary region. Thus, the slope correction data is generated, and the slope correction data is multiplied by the output components of R, Gr, Gb, B of the pixels existing in a predetermined width on the right side of the boundary region, respectively. Make corrections. As described above, stitching correction (signal level difference correction) processing is performed.

  In the case where the signal unevenness is corrected in step S17, the region A designated as the enlarged display region includes an image peripheral region in which the signal unevenness occurs due to the divided exposure process at the time of manufacturing the image sensor 10. Generates slope correction data from the image data adjacent to the image peripheral area for correcting signal unevenness that changes in a slope shape toward the edge of the image sensor 10 in the image peripheral area, and uses the slope correction data. Thus, the signal unevenness in the peripheral area of the image is corrected. Further, when correcting the signal unevenness in step S17, if the area A designated as the enlarged display area includes the pixel defect area of the image sensor 10, the correction for correcting the signal unevenness in the image defect area is performed. Data is generated from image data adjacent to the pixel defect area, and signal irregularities in the pixel defect area are corrected using the correction data.

  After correcting the image data signal level difference as described above, it is sent to the LCD display unit 17 and the through image is enlarged and displayed (step S18). If the enlargement display area and the enlargement magnification are designated again, the process returns to step S11 and the processes of steps S11 to S18 are repeated. When the end of displaying the through image is instructed by a selection button (not shown) provided on the operation unit 19 (step S19), the supply of power to the LCD display unit 17 is stopped and the through image is displayed. The image display ends.

  According to the imaging apparatus according to the present embodiment, when displaying a through image, whether or not to correct signal unevenness generated in the image data due to the boundary region of the image sensor or the like is enlarged and displayed. Since control is performed according to the magnification of the area and the through image, signal unevenness generated in the image data can be corrected only when necessary, and the load on the signal processing unit or the like based on the correction of signal unevenness can be increased. It is possible to prevent the generation of heat. In addition, it is possible to display a through image with good image quality for a long time.

  Further, in the above-described embodiment, when the temperature of the image sensor 10 detected by the temperature sensor 18 exceeds a predetermined temperature, the LCD display unit 17 is performing the enlarged display of the through image and correcting the signal unevenness. If it is performed, the correction of the signal unevenness may be stopped while the enlarged display of the through image is continued. In this case, heat generation can be reduced because the load on the signal processing unit is reduced.

  Further, in the above-described embodiment, when the temperature of the image sensor 10 detected by the temperature sensor 18 exceeds a predetermined temperature, the display of the through image on the LCD display unit 17 is set to a non-enlarged display or the through image is displayed. The display may be stopped. In this case, since the load on the signal processing unit is further reduced, heat generation can be reduced and power consumption can be reduced. Note that a warning display may be performed before the non-enlarged display or the display of the through image is stopped.

  Further, in the above-described embodiment, when the area designated as the enlarged display area includes a predetermined area such as the boundary area of the image sensor 10, the correction amount of the signal unevenness in the designated enlargement ratio and the designated area is set. Based on this, it is determined whether or not to correct the signal unevenness, but it is determined whether or not to correct the signal unevenness based on the specified magnification or the amount of correction of the signal unevenness in the specified area. It may be.

  In the above-described embodiment, the designation of the enlarged display area and the designation of the enlargement magnification may be designated by the same designation unit, or may be designated by different designation units.

It is a block block diagram of the digital camera which concerns on embodiment. It is a figure for demonstrating the area | region which implements correction of the signal nonuniformity which concerns on embodiment. It is a flowchart for demonstrating operation | movement of the digital camera which concerns on embodiment. It is a figure which shows the arrangement | positioning state of the color filter with respect to each pixel of an image pick-up element. It is a figure which shows the designation | designated state of the expansion area | region for performing a through image display. It is a figure for demonstrating stitching correction | amendment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Digital camera, 10 ... Image sensor, 11 ... CPU, 12 ... Image sensor drive circuit, 13 ... Analog signal processing circuit, 14 ... A / D conversion circuit, 15 * ··· Pre-signal processing unit, 16 ... signal processing unit, 17 ... LCD display unit, 18 ... temperature sensor, 19 ... operation unit, 20 ... storage unit.

Claims (6)

An image sensor that images subject light and outputs an image signal;
A display unit for displaying a through image based on image data generated from the imaging signal;
A designation unit for designating an enlarged display area of a through image in the display unit;
A determination unit for determining whether or not the enlarged display region specified by the specification unit is a predetermined region;
A correction unit that performs correction processing of signal unevenness that occurs in the image data when the determination unit determines that the predetermined region and execution of enlarged display is instructed;
An imaging apparatus comprising: A magnification designating unit for designating an enlargement magnification when performing the enlarged display;
The imaging apparatus according to claim 1, further comprising: a correction control unit that controls whether or not the correction process is performed by the correction unit based on the enlargement magnification specified by the magnification specifying unit. A storage unit for storing a correction amount of the signal unevenness for each predetermined region;
The correction control unit controls whether or not to perform the correction processing by the correction unit based on a correction amount of the signal unevenness for each of the predetermined areas stored in the storage unit. The imaging device according to claim 1 or 2.   4. The predetermined area includes at least one of a boundary area, an image peripheral area, and a pixel defect area generated due to a divided exposure process at the time of manufacturing. The imaging device according to one item. A temperature sensor for detecting the temperature of the image sensor or the vicinity thereof;
The imaging apparatus according to any one of claims 1 to 4, wherein when the detected value by the temperature sensor exceeds a predetermined temperature, the correction process by the correction unit is stopped.   6. The display of a through image on the display unit is set to a non-enlarged display or the display of the through image on the display unit is stopped when a detection value by the temperature sensor exceeds a predetermined temperature. Imaging device.

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